The present invention relates to a drive for an elevator installation.
An elevator installation consists of a car for reception of goods or persons to be transported and a counterweight, or a second car, which are connected together by way of supporting and driving means via a drive. The drive of the elevator installation in that case has the object of driving the driving and supporting means and thus an alternate raising and lowering of the car and the counterweight.
The drive consists of the principal components of a drive pulley, a motor and a brake. The drive pulley receives the supporting and driving means and transmits drive forces to the supporting and driving means by way of a mechanically positive or friction couple. The motor for its part drives the drive pulley, and the brake brakes the drive pulley. The motor, the brake and the drive pulley are accordingly connected together in terms of force and torque.
A drive for an elevator is shown in the European patent document EP 1 400 477 in which a motor drives drive pulleys by means of a drive shaft and the drive pulleys are braked by a brake. The drive pulleys are in that case, in a preferred form of embodiment, arranged between the motor and the brake unit. The drive pulleys drive flat belts. This allows use of small drive pulley diameters. The drive can thereby be of small and compact construction. Drives of this kind usually require a signal transmitter. The signal transmitter detects the rotational movement of the drive shaft and thus enables a speed or position determination of the moving bodies. Commercially available signal transmitters contain a rotating part, which has a readable mark or a coding and which is connected with the drive shaft, and a stationary part, which contains a reading device in order to read the mark or coding. The markings are, for example, of an inductive, magnetic or optical kind. In a common arrangement, the signal transmitter is fastened to an extended end of the drive shaft.
However, this attachment of a signal transmitter contains disadvantages. The attachment needs space and requires a precise and thus costly production.